Paraliroceras macrogaster Korn & Hairapetian, 2025, sp. nov.
Year: 2025
Type: other
Abstract: Paraliroceras macrogaster sp. nov. urn:lsid:zoobank.org:act: 0AF97520-0593-4555-9D0F-96A5FBF603A6 Fig. 26; Table 20 Diagnosis Species of Paraliroceras with thinly globular, subinvolute conch (ww/dm ~ 0.86; uw/dm ~ 0.23), moderately depressed whorl profile (ww/wh ~1.90) and very high coiling rate (WER ~2.35) at a conch diameter of 60 mm. Whorl profile with broadly arched venter and flanks, narrowly rounded umbilical margin, flattened and steep umbilical wall and moderately wide imprint zone (IZR ~ 0.22). Without sculpture. Suture line with very shallow and wide external, lateral and umbilical lobes. Etymology From the Greek ‘μακρός’=‘large’ and ‘γαστήρ’= ‘abdomen’; because of the broadly rounded flanks and venter. Type material Holotype IRAN – Esfahan Province • Baghuk Mountain; Hambast Formation, Araxoceras beds (early Wuchiapingian); 2011; Korn et al. leg.; illustrated in Fig. 26A–C; MB.C.32141. Paratype IRAN – Esfahan Province • 1 specimen; Baghuk Mountain; same data as for holotype; illustrated in Fig. 26D–F; MB.C.32142. Description Holotype MB.C.32141 is a fully chambered, incomplete specimen with a conch diameter of 62 mm, in which the right side is incomplete. Some conch dimensions can thus only be reconstructed (Fig. 26A). The conch is thinly globular and subinvolute (ww/dm ~ 0.87; uw/dm =0.22) with a very high coiling rate (WER= 2.39) and a moderately deep whorl overlap (IZR =0.23). The whorl profile is moderately depressed (ww/wh ~ 1.91) with a broadly convex venter that merges continuously with the flanks. The umbilical margin is narrowly rounded and pronounced; the umbilical wall is steep and almost flat (Fig. 26B). The suture line shows very broad and shallow lobes on venter, flanks and umbilical wall (Fig. 26C). The last volution possesses 15 phragmocone chambers without an indication of crowding (CLI=24). The siphuncle has a dorsocentral position. Paratype MB.C.32142 is almost completely chambered and, with a conch diameter of 60 mm (Fig. 26D– E), has very similar conch parameters to the holotype. The umbilical margin is slightly more rounded and the suture line has a slightly deeper external lobe (Fig. 26F). The last volution of the phragmocone has about 15 chambers (CLI=24). Remarks Paraliroceras macrogaster sp. nov. with its pronounced, narrowly rounded umbilical margin makes a separation from the other late Permian representatives of the family Liroceratidae rather easy. Paraliroceras macrogaster has a very similar conch to P. kazanicum, but differs from P. kazanicum (with IZR = 0.15 and WER = 2.80) in the higher whorl overlap rate of the whorls (IZR = 0.22) and the lower coiling rate (WER=2.35).
Authors: Korn, Dieter, Hairapetian, Vachik
Institutions: Museum für Naturkunde, Islamic Azad University, Isfahan
Language: English
Subfield: Paleontology
Field: Earth and Planetary Sciences
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7083707444
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